Broadband combining system with high spectrum efficiency for use in wireless communications

Abstract

A system for combining a plurality of signals in a wireless communication device employs a plurality of base station duplexers each coupled to a corresponding base station from a plurality of collocated base stations, each base station capable of receiving and transmitting signals in accordance with a corresponding transmission protocol. Each duplexer includes a transmit and receive paths for allowing signals to be transmitted from the base station and further allowing signals to be received by the base station. Isolators are each coupled to a corresponding one of the transmit path of each of the duplexers. Bandpass filters are each coupled to an output port of a corresponding one of the isolator and a combiner receives signals provided by each one of the band pass filters. An antenna duplexer is coupled to an output port of the combiner via a transmit path, where the duplexer provides a combined signal of the collocated base stations to an antenna. The duplexer further includes a receive path for providing signals received by the antenna to a corresponding receive path of each of the base station duplexers.

1. A system for combining a plurality of signals in a wireless communication device, said system comprising:
 a plurality of base station duplexers each coupled to a corresponding base station from a plurality of collocated base stations each base station capable of simultaneously receiving and transmitting signals in accordance with a corresponding transmission protocol; 
 wherein each duplexer includes transmit and receive paths for allowing signals to be transmitted from the base station and further allowing signals to be received by the base station in accordance with different protocols; 
 isolators, including ferrite broad band isolators, exhibiting at least a 20 dB isolation, each coupled to a corresponding one of said transmit path of each of said duplexers; 
 bandpass filters, each coupled to an output port of a corresponding one of said isolator, and each exhibiting high impedance, with substantially an open circuit characteristic, at rejection frequencies, configured to tune with a center frequency and a band pass range that is substantially equal to the center frequency and bandwidth of the transmitted signal; 
 a combiner for receiving signals provided by each one of said band pass filters; and 
 an antenna duplexer coupled to an output port of said combiner via a transmit path, said duplexer providing a combined signal of said collocated base stations to an antenna, said duplexer further including a receive path for providing signals received by said antenna to a corresponding receive path of each of said base station duplexers. 
 
     
     
       2. The system in accordance with  claim 1 , wherein said isolators are connected to a Chebyscheff or elliptic function filter. 
     
     
       3. The system in accordance with  claim 1 , wherein said filters exhibiting high impedance are interdigital printed circuit type filters. 
     
     
       4. The system in accordance with  claim 1 , wherein a transmission line connecting said band pass filters to said combiner has an electrical length substantially equal to an even number of quarter wavelength of a corresponding filter. 
     
     
       5. A system for combining a plurality of signals in a wireless communication device, said system comprising:
 a plurality of base station duplexers each coupled to a corresponding base station from a plurality of collocated base stations each base station capable of simultaneously receiving and transmitting signals in accordance with a corresponding transmission protocol; 
 wherein each duplexer includes transmit and receive paths for allowing signals to be transmitted from the base station and further allowing signals to be received by the base station in accordance with different protocols; 
 isolators, including ferrite broad band isolators, exhibiting at least a 20 dB isolation, each coupled to a corresponding one of said transmit path of each of said duplexers; 
 bandpass filters, each coupled to an output port of a corresponding one of said isolator and each exhibiting low impedance, with substantially a short circuit characteristic, at rejection frequencies, configured to tune with a center frequency and a band pass range that is substantially equal to the center frequency and bandwidth of the transmitted signal; 
 a combiner for receiving signals provided by each one of said band pass filters; and 
 an antenna duplexer coupled to an output port of said combiner via a transmit path, said duplexer providing a combined signal of said collocated base stations to an antenna, said duplexer further including a receive path for providing signals received by said antenna to a corresponding receive path of each of said base station duplexers. 
 
     
     
       6. The system in accordance with  claim 5 , wherein said filters exhibiting low impedance are cavity type filters with impedance close to a short circuit. 
     
     
       7. The system in accordance with  claim 5 , wherein a transmission line connecting said band pass filters to said combiner has an electrical length substantially equal to an odd number of quarter wavelength of a corresponding filter. 
     
     
       8. A system for combining a plurality of signals in a wireless communication device, said system comprising:
 a plurality of base station duplexers each coupled to a corresponding base station from a plurality of collocated base stations each base station capable of simultaneously receiving and transmitting signals in accordance with a corresponding transmission protocol; 
 wherein each duplexer includes transmit and receive paths for allowing signals to be transmitted from the base station and further allowing signals to be received by the base station in accordance with different protocols; 
 isolators, including ferrite broad band isolators, exhibiting at least a 20 dB isolation, each coupled to a corresponding one of said transmit path of each of said duplexers; 
 a plurality of bandpass filters each coupled to an output port of a corresponding one of said isolators, and each exhibiting high impedance, with substantially an open circuit characteristic, at rejection frequencies, each configured to tune with a center frequency and a band pass range that is substantially equal to the center frequency and bandwidth of the transmitted signal; 
 a plurality of circulators coupled in series, wherein each circulator is configured to receive signals from two of said band pass filters; and 
 an antenna duplexer coupled to an output port of one of said circulators via a transmit path, said duplexer providing a combined signal of said collocated base stations to an antenna, said duplexer further including a receive path for providing signals received by said antenna to a corresponding receive path of each of said base station duplexers. 
 
     
     
       9. The system in accordance with  claim 8 , wherein the number of said band pass filters is one less than the number of said isolators. 
     
     
       10. The system in accordance with  claim 9  wherein an output port of the last circulator in said series of coupled circulators is coupled to said antenna via said antenna duplexer. 
     
     
       11. The system in accordance with  claim 8 , having a plurality of circulators coupled in series, providing an arrangement for combination of signals from all base stations. 
     
     
       12. The system in accordance with  claim 11 , wherein first one of said base stations operate in LTE mode and second one of said base stations operate in CDMA mode. 
     
     
       13. A system for combining a plurality of signals in a wireless communication device, said system comprising:
 a plurality of base station duplexers each coupled to a corresponding base station from a plurality of collocated base stations each base station capable of simultaneously receiving and transmitting signals in accordance with a corresponding transmission protocol; 
 wherein each duplexer includes transmit and receive paths for allowing signals to be transmitted from the base station and further allowing signals to be received by the base station in accordance with different protocols; 
 isolators, including ferrite broad band isolators, exhibiting at least a 20 dB isolation, each coupled to a corresponding one of said transmit path of each of said duplexers; 
 a plurality of bandpass filters each coupled to an output port of a corresponding one of said isolators, and each exhibiting low impedance, with substantially a short circuit characteristic, at rejection frequencies, each configured to tune with a center frequency and a band pass range that is substantially equal to the center frequency and bandwidth of the transmitted signal; 
 a plurality of circulators coupled in series, wherein each circulator is configured to receive signals from two of said band pass filters; and 
 an antenna duplexer coupled to an output port of one of said circulators via a transmit path, said duplexer providing a combined signal of said collocated base stations to an antenna, said duplexer further including a receive path for providing signals received by said antenna to a corresponding receive path of each of said base station duplexers.